Vandenboschia Copel. ( Copeland 1938 )

Ahamada H. Saïd, Sabine Hennequin, Germinal Rouhan & Jean-Yves Dubuisson, 2017, Disentangling the diversity and taxonomy of Hymenophyllaceae (Hymenophyllales, Polypodiidae) in the Comoros, European Journal of Taxonomy 313, pp. 1-53 : 31

Genus Vandenboschia Copel. ( Copeland 1938)

In tropical Africa and the western Indian Ocean, three potential morphologically close Vandenboschia species (the genus is pantropical with more than 15 species) are reported in literature and often confused especially in collection: V. speciosa (Willd.) G.Kunkel , V. radicans (Sw.) Copel. and V. gigantea (Bory ex Willd.) Pic.Serm. Vandenboschia speciosa is distributed in the wettest places in Europe and in Macaronesia. Molecular data clearly distinguished Neotropical V. radicans from European V. speciosa ( Ebihara et al. 2007) .According to Kornaś (1994), continental African populations belong to V. radicans , but have been often misidentified as V. speciosa in collections. Because of the lack of molecular data for continental African specimens and in absence of clear morphological diagnostic characters for discriminating those species, the specific status of continental African Vandenboschia populations remains nevertheless unknown and questionable. Vandenboschia gigantea is also molecularly a clearly distinct species ( Dubuisson et al. 2013a, 2013b) a priori restricted to the western Indian Ocean. In absence of rhizomes, the highly-divided fronds with linear tapered ultimate segments of V. gigantea could be confused with those of many Abrodictyum spp., especially Abrodictyum pseudorigidum . But V. gigantea (as V. radicans and V. speciosa ) is a climbing species with a quite long-creeping branched rhizome, while Abrodictyum pseudorigidum is terrestrial with a short monocaulous erect rhizome. As detailed by Dubuisson et al. (2003), V. gigantea grows on the ground forming large populations in the understory, with individuals able to secondary climb on tree-trunks. Many herbarium specimens are reported as epiphytes because they correspond to the climbing parts only. In such cases, rhizomes can appear rootless because the developed root system is mostly present on the terrestrial parts and on the rhizomes that begin to climb at the base of trunks, but this species in fact always bears roots. Roux (2009) also reports V. radicans for the archipelago but our investigations indicate that only V. gigantea is present in the region. Thus, all specimens from the area that have been identified as V. radicans (or Trichomanes radicans ) refer actually to V. gigantea .